Door arrangements are known for aircraft having a fuselage with a fuselage structure that includes a door frame surrounding the door opening. The door arrangement has a door that is to be arranged inside the door frame and a door joint mechanism that is attached to the door and to the fuselage structure. For aerodynamic reasons, the outer contour of the door has to lie flush with the outer contour of the fuselage structure adjacent to the door frame. This aspect as well as the considerable thickness of the door due to the usual lightweight mode of construction make it necessary for substantial portions of the door to be situated inside the door frame when the door is in the closed position whereas, in order to reach an open position, the door has to be moved out of the door frame and partially or completely around an edge of the door frame into a position that is essentially outside of the fuselage. This calls for very complex kinematics of the door joint mechanism since the door has to be prevented from colliding with parts of the fuselage structure along the path of motion of the door.
If the fuselage of the aircraft has a pressurized cabin, which is the case for almost all large passenger aircraft nowadays, the door also has to be sealed off relative to the door frame during flight in order to prevent a loss of pressure from the pressurized cabin. This calls for sealing elements between the door and the surrounding fuselage structure or the surrounding door frame. In order to prevent the door from opening accidentally, especially during flight, it is also necessary to lock the door in the closed position. For this purpose, designs are normally employed that call for the door to be raised out of the locked closed position into an unlocked closed position or for the door to be lowered from the unlocked closed position into the locked closed position.
Especially those aircraft doors that are designed as pivoting emergency-exit doors or as emergency-exit hatches usually have to be guided over a very large pivoting angle range of 0° to 90° or more, but often of 0° to 180° or more, in order to be opened and closed. This large pivoting angle range, in conjunction with the above-mentioned necessary properties of the door and of the adjacent fuselage structure, require a quite complex door joint mechanism and this is another reason for the complexity of the kinematics of the door. Therefore, taking into consideration the above-mentioned requirements, conventional door arrangements for aircraft make use of a door joint mechanism having translational articulated elements that ensure the cited large pivoting angle range of the door under the above-mentioned conditions.
With such conventional door arrangements, however, it has been found that the translational articulated elements exhibit quite a lot of play and that they cannot always guide the door precisely over the large pivoting range. Moreover, due to the translational articulated elements, the position of all of the articulated elements involved when the door is being opened or closed is not unambiguously defined. Furthermore, when a door joint mechanism with translational articulated elements is used, the position of the door relative to the door frame cannot be defined precisely enough which, in turn, means that the sealing of the door against internal pressure of the cabin can only be realized with a great deal of effort and the sealing conditions are unfavorable. Moreover, when the door is in the open position, the transmission and application of the loads emanating from the opened door towards and into the fuselage structure are unfavorable.